1. Field of Invention
This invention relates in general to improvements and replacements of steel reinforcing in large concrete support foundations, precast or constructed in-situ, particularly useful for supporting tall, heavy structures including towers which may be used to support wind turbines, power transmission lines, street lighting and signals, bridge supports, commercial signs, freeway signs, ski lifts, and the like.
More specifically, the continuous strand hoop reinforcement of the present invention may be high strength steel strand or cable sleeved to allow post tension useful in compressing the concrete to exceed loads and splitting stresses in the concrete between other reinforcements with minimal deflection and distortion while reducing the steel weight, volume and length currently required of conventional rebar hoops by as much as one-half.
2. Description of Related Art
My earlier U.S. Pat. No. 5,586,417 (my '417 patent) for tensionless pier foundation, U.S. Pat. No. 5,826,387 for pier foundation under high unit compression, U.S. Pat. No. 6,672,823 for perimeter weighted foundation, U.S. Pat. No. 7,533,505 for pile anchor foundation, U.S. Pat. No. 7,618,217 for post tension pile foundation, and U.S. Pat. No. 7,707,797 (my '797 patent) for pile anchor foundation disclose post-tensioned concrete foundations for large supporting structures for which the present invention is applicable. Accordingly, the disclosures of my six aforesaid U.S. patents are expressly incorporated herein by reference as if fully set forth in their entirety.
Conventionally, rebar hoops are circular (lateral) and positioned around and in contact with the vertical or horizontal reinforcing rebars or bolts of the concrete foundation. The rebar hoops are either circular or otherwise configured lengths of rebar lapped at ends sufficiently to provide bonding to the concrete and reinforcement equal to the strength of the steel rebar. The laps considerably increase the quantity of steel where larger diameter hoops are utilized, since additional rebar is required as the rebar steel strength is typically one-third the steel strength of the strand material.
Further, conventional hoops are utilized to prevent the separation of the foundation from occurring between the vertical or horizontal (lateral) steel reinforcing rebar or bolts. However, there is a need to provide hoop strands which can be post-tensioned in order to compress the concrete between the vertical or horizontal (lateral) steel reinforcing rebar or bolts and prevent cracking as well as reducing deflection, distortion, cycling, fatigue and increasing structure life.